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photocraft/docs/printing.md
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WolfandClaude Opus 5.5 2f08860383 Print: Portrait and Landscape in the Print dialog on Windows
On Windows the Print dialog takes the paper and its orientation from the
printer driver, and had no way to change the orientation short of the
driver's own Print Settings… dialog. Photoshop has Layout buttons for it.
A print laid out landscape on portrait driver settings (from a script,
the CLI or another app) stopped with "the driver paper or orientation
differs from the print layout".

- The dialog has an Orientation row (Portrait, Landscape) under Print
  Settings…. It turns the driver settings through file.print.page and
  takes the paper from the driver again, so the paper and preview turn.
- file.print.page takes "orientation": "portrait|landscape" and returns
  the turned settings as printerSettings, with the page they give.
- print_windows turns the settings (the given ones or the printer's
  defaults) to the layout's orientation when the driver has the layout's
  paper the other way round; another paper is still refused.

Turning sets dmOrientation and its dmFields bit in the DEVMODE and keeps
every other byte, the driver's private settings included; the driver
validates the result as it does settings from Print Settings…. No new
UI strings: "Orientation", "Portrait" and "Landscape" are in every
catalog.

Tests: the turned settings (orientation set, all else kept, with and
without private driver bytes), when a paper counts as turned, an unknown
orientation refused before any printer is asked, the dialog's reading of
the driver paper and its error path, and, run by hand on Windows, a
real "Microsoft Print to PDF" driver turning for a landscape layout.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-19 21:46:41 +02:00

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Printing

File › Print renders the flattened document onto one PDF page (paper size and orientation, position and scale, crop and registration marks, labels, colour handling) and hands that page to a printer. The rendering is print_cmds.rs in photocraft-engine, shared by the dialog, the batch commands and automation (file.print, file.printOneCopy); this page is about the hand-off.

Routes to the printer

Route When What the user sees
craft-print (lp on CUPS, the Windows spooler) Whenever lp is on the path (macOS, Linux outside a sandbox) or on Windows Sent to the printer (request id is Office-42)
CUPS over IPP (photocraft-ipp) No lp on the path (a Flatpak) and a print server answers: CUPS_SERVER, then /run/cups/cups.sock, /var/run/cups/cups.sock, /private/var/run/cupsd, then localhost:631; always for a printServer named in the request Sent to the printer (job 42 on Office)
Print portal (org.freedesktop.portal.Print, desktop app on Linux) No print server reachable or no printer set up, or always with PHOTOCRAFT_PRINT_PORTAL=1 The system print dialog, seeded with the copies and paper; the outcome goes to the log
Print to PDF output given (the Output field of the dialog) The file; nothing is spooled unless send is true

A route that exists but fails (an unknown printer, a job the queue refuses) is an error; only a missing route (no lp, no print server, no printer) moves on to the next one.

The IPP client is in-process, pure Rust (RFC 8010/8011: CUPS-Get-Printers, CUPS-Get-Classes, CUPS-Get-Default, Print-Job with the PDF as the document), so no lp binary is needed. That is what makes printing work in the Flatpak: the manifest grants --socket=cups, which mounts the host's CUPS socket, and the sandbox has no lp. On a system without CUPS, or in a sandbox without the socket, the app falls back to the print portal, whose dialog runs outside the sandbox.

Which printer

The dialog's Printer field, or "printer" in the command, names a queue (case-insensitively; a CUPS class counts, as with lp -d). Left empty, the server's default printer is used; without a default, the only printer; with several and no default, the error names them. With no printer at all, the portal takes over when it is available, otherwise the error says to add one in the system settings or print to PDF.

file.printers lists what the print server knows: {"printServer": "host[:port]|socket"} is optional and defaults to the system's CUPS; the result is {server, default, printers: [{name, info, state, acceptingJobs, default, class}]}, or an empty list with a note when no server answers. "printServer" on file.print sends one job to a named server; "dryRun": true renders the page and reports the equivalent lp command without spooling.

Orientation (Windows)

On Windows the paper and its orientation are the driver's: the Print dialog takes them from the printer's settings. Its Orientation buttons (Portrait, Landscape; Photoshop's Layout) turn those settings, as Print Settings… would, and the paper and preview turn with them. file.print.page {"orientation": "portrait|landscape"} does the same for scripts: it returns the turned settings as printerSettings, with the page they give. A print sent to a Windows printer whose layout is the driver's paper the other way round (a landscape layout, portrait settings) turns the settings to the layout before printing, rather than stopping with "the driver paper or orientation differs"; another paper is still refused.

Results

file.print returns sent, backend (lp, windows, ipp, portal), spooler (where the job went) and pdf (the page's path, only when output named one).

Environment

Variable Effect
CUPS_SERVER The print server, as CUPS itself reads it: host[:port] or a socket path
PHOTOCRAFT_PRINT_PORTAL=1 Always use the system print dialog (the portal) instead of lp or CUPS directly
PHOTOCRAFT_PRINT_PORTAL=0 Never use the portal; a missing print server is then an error

Verification

  • crates/ipp/src/tests.rs: the client against a fake CUPS over TCP and a Unix socket: printer listing with state and default, the default printer and its absence, Print-Job with the document and the job id, chunked and content-length replies, HTTP and IPP error statuses, broken replies.
  • crates/engine/src/print_cmds/tests.rs: printer resolution (requested, default, only one, several without a default, unknown, none); a complete file.print against a fake CUPS (printer URI, copies, job name, document format, the PDF itself) and file.printers; lp taking the job when it is on the path; the IPP route when it is not (a child process with an empty path); the app's spooler when preferred, as the fallback without a printer, and skipped when a server is named; print to PDF untouched.
  • apps/photocraft/src/print_portal.rs: the request path rule and the paper/copies seeding of the dialog (PWG names for the standard papers, millimetres for custom sizes).